My FFT analysis says that they both have tones at about 7880 and 15950 Hz, but in V they are about -80 and -78 dB down while in w they are -98 and -96 dB down. The noise floor of V is abut 6 dB higher above 5 KHz. The two noise floors are similar enough to raise some questions in my mind.

The fact that both noise floors are dominated by 120 Hz hum s at similar levels suggests to me that the source of the noise may be other parts of the test environment, perhaps even acoustical noise that is picked up by the mics.